Monolithic Power Systems Inc. MP3900DK-LF-P

Overview

MP3900DK-LF-P from Monolithic Power Systems is a high-efficiency, constant-frequency peak current mode boost controller driving external N-channel MOSFETs up to 10A peak inductor current. It features 330kHz switching frequency, 180µA quiescent current, 10V gate driver output, and lossless current sensing for V_ISENSE < 30V - enabling direct drain-sense in low-voltage boost applications such as 25V/2A TV CCFL power supplies.

For engineers reviewing the MP3900DK-LF-P datasheet, MP3900DK-LF-P pinout, MP3900DK-LF-P application, or MP3900DK-LF-P equivalent, key selection criteria include its 0.816V feedback reference, cycle-by-cycle current limiting at 200mV ISENSE threshold, thermal shutdown at 150°C, and compatibility with boost, SEPIC, flyback, and forward topologies under –40°C to +85°C operation.

Technical Context

The MP3900DK-LF-P implements a fixed-frequency (270–390kHz) peak current mode control architecture with internal slope compensation and an error amplifier transconductance of 0.36mA/V. Its COMP/RUN pin serves dual functions: enabling the IC via 0.14V threshold and providing compensation node for loop stability.

It integrates undervoltage lockout (8.9V turn-on, 2.3V hysteresis), 10V gate driver with 4Ω sink/16Ω source impedance, and an IMAX clamp limiting sensed current to 200mV - directly setting peak inductor current without external sensing resistors when V_ISENSE stays below 30V.

Key Specifications

Pinout & Package

MP3900DK-LF-P is housed in an 8-pin MSOP package (3.0mm × 3.0mm, 0.65mm pitch) with exposed thermal pad for enhanced power dissipation (θ_JA = 150°C/W). Pin 6 is NC; all other pins are functionally defined per Monolithic Power Systems' Rev. 1.0 datasheet.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar boost controller applications.

Compared with LM5022MM/NOPB and UCC28064DR, MP3900DK-LF-P delivers superior light-load efficiency due to 180µA IQ and lossless sensing, while offering simpler loop compensation than average-mode controllers - making it optimal for cost-sensitive, fixed-input industrial boost supplies.

Availability

MP3900DK-LF-P is available at Aetrix Electronics and suitable for TV CCFL power generation, telecom isolated power, and industrial off-line controller applications requiring stable component supply, RoHS-compliant packaging, and long-term lifecycle support.

Supply support for MP3900DK-LF-P includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-performance analog and power ICs, with design centers in the US, China, and Taiwan, and global manufacturing partnerships.

The MP3900 belongs to MPS's high-efficiency DC-DC controller product line, engineered specifically for non-isolated boost, SEPIC, and flyback topologies in telecom, industrial, and consumer power systems where low IQ, thermal robustness, and simplified layout are critical.

FAQ

Can MP3900DK-LF-P operate with input voltages below 8.9V?

No. The device incorporates an undervoltage lockout (UVLO) with a turn-on threshold of 8.9V ±0.3V and 2.3V hysteresis. Below 8.6V, the IC remains disabled and draws only 10µA shutdown current. Operation requires V_CC ≥8.9V to initiate switching.

Is the ISENSE pin compatible with 40V drain voltage in flyback configuration?

No. The ISENSE pin has an internal clamp rated for 36V maximum, but Monolithic Power explicitly warns against direct connection to MOSFET drain if voltage swing exceeds 30V. For 40V applications, use an external current-sense resistor and scale accordingly to stay within 200mV limit.

What is the minimum recommended output capacitance for stable 25V/2A operation?

Per the datasheet's ripple calculation and typical application (page 1), four parallel 4.7µF X7R ceramic capacitors (total 18.8µF, 50V rating) are specified. This meets both 1% output ripple requirement and 2.64A RMS ripple current rating at 330kHz switching frequency.

Does MP3900DK-LF-P support synchronous rectification?

No. The MP3900DK-LF-P is a controller-only device with a single GATE output driving the high-side switch. It does not provide complementary or low-side gate drive signals required for synchronous rectification; external diode (e.g., SS16 Schottky) is mandatory in boost topology.

How is soft-start implemented, and can it be adjusted?

Soft-start is internal and fixed: a 0.5µA current charges the external capacitor on the COMP/RUN pin, gradually raising the error amplifier output. Start time is determined by C_COMP; increasing capacitance extends soft-start duration linearly - e.g., 10nF yields ~20ms, 100nF yields ~200ms.

What thermal derating applies above 25°C ambient?

MSOP8 package has θ_JA = 150°C/W. At T_A = 70°C, maximum allowable power dissipation drops to (125°C − 70°C)/150°C/W = 0.367W - below the 0.67W rated limit. Layout with thermal pad soldering and 2oz copper is essential to sustain full load above 50°C ambient.

Is the FB pin internally clamped, and what happens above 1.3V?

Yes. If FB voltage exceeds 1.3V, the IC enters test mode and disables the GATE driver immediately. This is a hard fault condition - not a soft limit - and requires power cycle or COMP/RUN reset to recover. Design must ensure FB never rises above 1.2V under any transient or fault condition.